The present invention generally relates to a high-voltage terminal in an engine ignition system, which is directly connected with a spark plug or an ignition coil of an engine and more particularly, to a construction for retaining a coiled spring inserted into the high-voltage terminal.
FIG. 1 shows a known ignition system disclosed in Japanese Patent Laid-Open Publication No. 3-47475 (1991). In FIG. 1, a high-voltage terminal 2 is embedded in a high-voltage tower 1 and an electrically conductive coiled spring 5 for electrically connecting the high-voltage terminal 2 and a head terminal 4 of a spark plug 3 is inserted into a hollow of the high-voltage terminal 2. An insertion end 5a of the coiled spring 5 should be fixed to the high-voltage terminal 2 so as to prevent dropping by gravity of the coiled spring 5. To this end, an annular groove 2a is formed on a side wall of the hollow of the high-voltage terminal 2 and an outside diameter d1 of the insertion end 5a of the coiled spring 5 is so set as to be larger than an outside diameter d2 of the coiled spring 5, i.e. d1&gt;d2 as shown in detail in FIG. 2. Thus, while the insertion end 5a is being radially compressed by rotating the coiled spring 5 in its winding direction, the coiled spring 5 is inserted into the hollow of the high-voltage terminal 2 such that the insertion end 5a is brought into engagement with the groove 2a.
However, the known engine ignition system has such a drawback that since it is difficult to insert the large-diameter insertion end 5a of the coiled spring 5 into the hollow of the high-voltage terminal 2, efficiency for inserting the coiled spring 5 into the hollow of the high-voltage terminal 2 is poor. Furthermore, the known engine ignition system is disadvantageous in that since the force of engagement of the coiled spring 5 with the groove 2a, namely, the force for fixing the coiled spring 5 to the groove 2a of the high-voltage terminal 2 is small, the coiled spring 5 is readily disengaged from the groove 2a when pulled outwardly.